Appendix: Pad Description

To match the pitch of 50$\mu$m silicon microstrip detectors an overall pitch of 50$\mu$m can be obtained by placing Helix128-2 chips side by side. The 128 analog input pads are located at the front of the chip w. r. t. the detector (see fig. 18) while all pins necessary to operate the chip, i. e. power supply, digital control lines and analog output, are located at the rear side. The chip's trigger output pads are placed at the bottom side (with the input pads left) due to the relaxed space requirements of the HERA-B Inner Tracking Detector which makes use of the comparator information. Digital signals are categorized as outlined in table 6. For a description of the analog pads refer to the text.

All pads have been given reference numbers. Counting starts with the uppermost pad of the front (i. e. detector) side (with the input pads left) and continues with the peripheral pads counterclockwise around the chip. Finally, the probe pads in the chip's interior are counted from bottom to top. For the geometrical location refer to figure 18 on page (Helix128-2), fig. 19 on page (Helix128-2.1), and fig. 20 on page (Helix128-2.2/2.3).

 

 

Type Description

input Digital CMOS input operating at -2V...+2V supply.

output Digital CMOS output operating at -2V...+2V supply.

input (int. pulldown) Digital CMOS input operating at -2V...+2V supply with internal pulldown resistor.

input (int. pullup) Digital CMOS input operating at -2V...+2V supply with internal pullup resistor.

output (open drain) Digital open drain output operating at -2V...+2V supply.

$$\Delta V_{Sig,notSig} \ge 350$$ LVDS-input